Never gave this thought before, but, even if there is no grinding, is there damage still done?
Been driving this way for years as it is cheap amusment when people see it happen and ask how it doesn't grind.
I know others here do it and have a better idea about it since I've never taken any of my gearboxes apart.
I figure if you can time it perfectly, then there's no damage, but if you're putting pressure on the sycros before it matches rpm and slips in, then you're causing premature wear on the syncros. How much? I dunno. I use the clutch and still try to shift in a way that minimizes the work the syncros have to do. Just a habit (except when autocrossing of course...)
Been doing it racing for years and haven't killed a trans yet. I actually only do it for down shifts. Up shifts I still clutch.
When I teach shifting I make all my students shift without the clutch to show them it is possible. It also gives them a better sense of what is going on inside the trans.
Prior to synchronous gear boxes everyone had to match revs to shift up and down. Now everyone is spoiled and just puts it into whatever gear they want at whatever speed.
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I only do it when I can't get my damn clutch to bleed and I have to drive to get a vacuum pump. 
I have an easier time up shifting without the clutch than down shifting. But then I can't heel-toe either so there's that.
I once lost my motorcycle clutch an hour away from home. Wouldn't disengage. Since motorcycles have sequential shifters, going up and down through the gears was fairly simple, especially with some intelligent use of the throttle (get on it if downshifting, roll off if upshifting).
The trick was the red lights. I'd have to get it down into 1st, then stall it out when I stopped. When the light turned green, hit the starter (I'd already disabled the clutch interlock), lurch it forward in gear, give it gas, and eventually the gas engine would take over from the starter motor and I could keep riding. 
That said, under normal conditions, I do use the clutch for every shift, car or bike.
- Justin
I started shifting (up and down... even into 1st) yrs ago.. came in really handy one night ... I'd left Asheville Fri after work going to Charlotte (~2 hr) to play in darts tournament . stopped Independence Blvd at a light I slipped the trans into neutral as usual ... as the light turned green my foot hit the floor as the cable broke.
shut it off, 2nd gear, starter... when it caught , drove on the the tourny site... did the same thing at mid-night and came home.... lots of fun... glad I had already learned 
understeer: when you hit the wall with the front end,,, oversteer: when you hit the wall with the back end.... horsepower: how hard you hit that wall.... torque: how far you drag that wall
I can float gears all day long in my Peterbilt but I could never do it in a car. Go figure. 
Minivans - Pleasing Soccer Moms since 1984....
I can shift a racing (dog box) tranny without a clutch with no problem. Never been able to make it work with a synchro box.
-Chris R.
I used to do it a lot 20 years ago when driving a dump truck. Man that clutch was stiff, especially hard the knee I tore up in a go-kart wreck the year before. Drove that truck off and on for two years with no problems. Of course I hated that truck and really didn't care too much about the transmission.
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Marty! wrote: I can float gears all day long in my Peterbilt but I could never do it in a car. Go figure.
I used to float gears all the time in the allison trans the Box trucks I drive had. Thankfully I was able to translate that over cars
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White_and_Nerdy wrote: I once lost my motorcycle clutch an hour away from home. Wouldn't disengage. Since motorcycles have sequential shifters, going up and down through the gears was fairly simple, especially with some intelligent use of the throttle (get on it if downshifting, roll off if upshifting). The trick was the red lights. I'd have to get it down into 1st, then stall it out when I stopped. When the light turned green, hit the starter (I'd already disabled the clutch interlock), lurch it forward in gear, give it gas, and eventually the gas engine would take over from the starter motor and I could keep riding.
this works with miatas if your clutch slave goes kablooey. thrice. just don't run out the battery.
I left foot brake about 80% of the time on the road and often downshift without the clutch. It's more fun with a lightened flywheel. Been doing this for years without issue but for the occasional mess-up.
When the clutch m/c was just about gone in my Miata and I had to drive it a couple days before I could replace it, I'd save the pressure for when it was absolutely necessary - that is, at a full stop. All other times, no clutch up or down, which was particularly entertaining in the winter on fresh Azenis. After the first few shifts, I caught on pretty quick. It certainly helps that Miatae have incredibly communicative gearboxes.
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If you're good at it, you can do it without doing any harm to the box, or undue wear on the synchros. Most of us are not good at it, and are hard on the synchros when we try it. Personally, I'm terrible at it with a synchronized automotive box.
I upshift and downshift without the clutch on a regular basis while delivering papers in my Civic.
It depends on how hard to push on the syncros. If timed perfect, and the action is quick, then no. But if you push on the shifter before so that when the RPM comes around it drops in, well you could be doing a lot of harm. If you push very lightly then you are just gliding the syncro on a film of oil, and there really is no wear.
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25 (and more) years ago we ran many four, six, eight, and a couple of 24 hour motorcycle endurance road races without using the clutch on upshifts. Everything from RD Yamahas to a built Kawasaki 750. No problems. I can't bring myself to try it in a car.
mad_machine wrote:Marty! wrote: I can float gears all day long in my Peterbilt but I could never do it in a car. Go figure.I used to float gears all the time in the allison trans the Box trucks I drive had. Thankfully I was able to translate that over cars
I float 'em in my FreightShaker. For some reason down is harder for me than up.
scariest thing I ever did with shifting with the clutch involved an Iveco box truck we had.. great little truck, but was a pain to work on as the cab did not flip, you had to all the work through a hatch in the floor.
I was warming it up one winter morning and had to slid over to the passengerside to grab some papers.. nudged the stubby shifter.. and it fell into gear with no effort. Must have nudged it right as the engine throbbed.. it was hell to get back into the driver's seat and stab the brake before it ran into the building
During the Sound Check, nobody can year you scream
I used to do it all the time in an 87 sentra I had. That was 20 years ago. I haven't tried ot in a long time. Maybe on the way home today I'll see if I still got it.
I used to do it in my 64 Spit and my 89 Nissan PU but not in a long time. Maybe I will try it on the way home today.
Well, it seems to be that it is no grind, no foul.
I'll be curious to see my syncs when I open up the gearbox though.
chuckles wrote: 25 (and more) years ago we ran many four, six, eight, and a couple of 24 hour motorcycle endurance road races without using the clutch on upshifts. Everything from RD Yamahas to a built Kawasaki 750. No problems. I can't bring myself to try it in a car.on my 500cc Kaw MkIII I used the clutch only at full stop... up/down it didn't matter and different from my cars the shifts were quicker than if I had used the clutch
understeer: when you hit the wall with the front end,,, oversteer: when you hit the wall with the back end.... horsepower: how hard you hit that wall.... torque: how far you drag that wall
I shifted a lot without the clutch on my old motorcycles but I never really did it on the VFR or SV for some reason, I guess I never thought of it.
Formerly jdmae92
I stopped doing that when I blew the tranny on my Fairmont about 20 years ago. I don't know if the no clutch shifting was the cause, but I don't want to test the theory anymore.
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